Liquid fuel burner with oil precirculation



Dec. 25, 1951 R JOYCE 2,579,829

LIQUID FUEL BURNER WITH OIL PRECIRCULATION Filed Jan. 6, 1950 2SHEETSSHEET l 20 ZOa 20b FIG. I

L INVENTOR JOHN RUSKIN JOYCE BY: W/W/m HIS ATTORNEY Dec. 25, 1951 JJOYCE 2,579,829

LIQUID FUEL BURNER WITH GIL PRECIRCULATION Filed Jan. 6, 1950 2SHEETS-SHEET 2 INVENTOR JO N RUSKIN JOY E. BY"- H IS ATTORNEY PatentedDec. 25, 1951 LIQUID FUEL BURNER WITH OIL PRECIRCULATION John RuskinJoyce, London, England, assignor to Shell Development Company, SanFrancisco, Calif., a corporation of Delaware Application January 6,1950, Serial No. 137,063 In Great Britain January 10, 1949 16 Claims.(01.299-118) v This invention relates to liquid fuel burners it having apressure nozzle of the type which comprises a vortex chamber fed withfuel under pressure from a fuel supply duct through a tangential swirlport or ports and having a final outlet orifice through which the fuelemerges as aspray.

' In burners of the foregoing kind it is frequently necessary ordesirable to pre-circulate the liquid fuel through the body of theburner to a point adjacent to the burner tip before the burner is openedup. Thus, for example, when the burner is used to burn heavy fuel oilswhich are solid or semi-solid at normal temperatures, it is desirable topre-heat the oil remaining in the burner from a previous operationbefore the burner is opened ,up, by precirculating heated fuel oilthrough the body of the burner. Again, where a combustion chamber isprovided with a plurality of burners, some of which may be shut downunder conditions of light load, it is advantageous to circulate coldliquid fuel through the burners so shut down in order to cool them andthus protect them from damage by heat from the flame of other burnersremaining in operation. It is to be understood that the termpm-circulation," as used herein, includes circulation of liquid fuelthrough the body of the burner at any period when the burner is not inoperation.

In the applicants copending application Ser. No. 49,732, filed September17, 1948, a burner of the aforesaid kind is disclosed and claimed. Theembodiments described therein have a burner tip provided with a vortexchamber having one or more swirl ports for admitting liquid fuelthereinto from a fuel supply duct with a rotating motion, a forwardfinal outlet orifice, and a spill outlet for the rearward discharge offuel into a spill return duct, and a control memher is provided tocontrol the effective area of the swirl port or ports and of the spillof fuel through the spill duct, and wherein the control member in thezero output position thereof (corresponding to zero fiow of fuel throughthe outlet orifice) permits or establishes communication between thefuel supply duct and the vortex chamber for flow of fuel-through thelatter and into the spill return ductadjacent to the vortex chamber.Additionally, a valve is provided close to the final outlet orifice; thevalve is connected for actuation by the control member to close theoutlet orifice when the control member is moved to its zero outputposition and to open the outlet orifice when the control member moved ochamber.

the fuel delivery positions. In the preferred and simplest form ofthisburner the aforesaid valve comprises a valve head fixed to a stempassing through the spill outlet of the vortex In the case of thesmaller sizes of burner, however, this construction of the valve issomewhat diificult to manufacture with the required degree of accuracy,more especially since the stem has to be substantially smaller indiameter than the spill outlet in order that the latter shall not beunduly obstructed.

The present invention is an improvement in the burner of the aforesaidpatent application which enables pre-circulation of the fuel to a pointadjacent to the burner tip to be attained with a simpler and more robustform of valve. According to the present invention a liquid fuel burnerhaving a pressure atomizing nozzle having a pre-orifice chamber,preferably of the type comprising a pre-orifice vortex chamber fed withliquid fuel under pressure from a fuel supply duct through one or moretangential swirl ports, and having a final discharge orifice throughwhich the fuel emerges as a. spray, is provided with a pro-circulationduct communicating at one end through a pre-circulation shut-off valvewith the fuel supply tank and extending forwardly, e. g., through thebody of the burner, to a point adjacent to the burner tip, at whichpoint the pre-circulation duct communicates with the fuel supply ductexternally of the pre-ori'fice chamber. The burner has a tip valveadapted to shut off the final orifice from the fuel supply duct andurged by resilient means into the shut-off position. A part of the valveis subjected to the pressure of the fuel in the pre-circulation duct sothat when the precirculation shut-off valve is closed the resultantincreased pressure causes the tip valve to open and establishcommunication between the final orifice and the fuel supply duct.

When the burner is provided with a spill return duct, such duct mayadvantageously be constituted by a bore extending through theo'bturating end of the tip valve.

The invention will be described in detail with reference to theaccompanying drawings forming a part of this specification and showingcertain illustrative embodiments thereof, wherein:

Fig. 1 is a longitudinal sectional view of a burner according to theinvention, the tip valve being shown in closed position;

Figs. 2 and 3 are transverse sectional views taken alon correspondinglynumbered section nes on Figs. 8 and 1, respectivehl;

taken.along correspondingly numbered section lines on Fig. 1; and

Fig. 8 is a longitudinal sectional view of the rear end of the burnerwith the plunger and tip valve retracted, showing the opening of thespill valve.

Referring to the drawings in detail, the burner comprises a hollowcylindrical casing III in which is fitted a tubular inner body member.II which is of generally cylindrical shape. The inner wall of the casingand the outer wall of the body member have a close flt throughout themajor portion of the circumference, but are so formed as to constitute,with each other, two separate longitudinal ducts l2 and I3 parallel tothe axis of the burner. Thus, for example, the inner body member ll maybe provided with a pair of longitudinal cut-away portions or flats atits sides and spaced diametrically as shown. Duct 12 serves as the fuelsupply duct and duct l3 as the pro-circulation duct. These ducts arejoined at a point adjacent'to the burner tip by a circumferential grooveI4 formed in the periphery of the inner body member. The forward part ofthe body constitutes a nozzle portion and contains the pre-oriflcechamber I6, preferably of the vortex type. Swirl ports I5 are formed inthe body member, communicating at their outer ends with the base of thegroove, and inclined tangentially with respect to the wall of thechamber l6 for delivering fuel tangentially into the pre-oriflce vortexchamber IS. The pre-orifice vortex chamber is formed in any suitablemanner at the forward end of the burner casing, for example, by mountingan orifice plate I! between the end of the body member II and the flangeIlla at the front of the casing Ill (Fig. 4), the plate having a finaloutlet orifice I8 and constituting an orifice means. This platehas acylindrical boss l9 extending rearwardly into the'bore of the bodymember II and presenting a, frustoconical end wall. The vortex chamberis bounded forwardly laterally bv the bore wall of the body member I land at the rear by the tip valve, to .be described.

A generally cylindrical plunger 20, having an axial bore 20a is slidablymounted with n the bore of the inner body member I l and constitutes adisp aceable member for operating the burner.

The flt between the plunger and body memher is liquid-tight, at least atthe slightly enlarged forward part 201) of the plunger, so that theforward part 20b of the plunger can close the tangential swirl portswhen the plunger is in its forward position as shown in Fig. 1. In thisposition the said part of the plunger extends forwardly somewhat beyondthe swirl ports so that these ports remain covered during the initialpart of t "e rearward movement of the plunger and are mcovered only uponfurther retraction of the plunger. The forward end of the plunger,therefore, constitutes flow control means in the form of a slide valvefor the swirl ports. The foremost end of the plunger has a cylindricalpart 2| of reduced diameter which enters the vortex chamber l6 and theforward edge thereof is bevelled'to form a liquid-tight seat on thefrusto-conical interior face of the orifice plate I! when the plunger isin its foremost position. The foremost part of the plunger 20,

- body member ll.

therefore. constitutes the aforesaid tip valve. *The main, elongatedpart of the plunger 20, al-

though shown in the illustrative embodiment to be integral with theslide valve and with the tip valve, need not be integral and performstwo disl6 when the tip valve is retracted, as shown in Figs. 4 and 5permitting excess fuel-to spill back through the plunger; when the tipvalve is closed these bores are out of communication with the vortexchamber, but are still in communication with the orifice [8. The controlfunction will be described in the next paragraph.

The rear end of the plunger 20 is enlarged at 22 and flts acorrespondingly enlarged bore 23 of The flats on the sides of the bodymember ll commence somewhat in advance of the enlarged bore (see Fig.6), and the ends of the ducts l2 and l 3 are in communication with thefuel supply duct 24 and the pre-circulation duct 25 within the casing(see Figs. 3 and 6) respectively. Fuel is supplied to the duct 24 underpressure from any source, not shown, and fuel is discharged from duct 25through a shutoff valve 26 for return to a fuel reservoir (not shown).The enlarged part 22 of the plunger terminates at its forward endadjacent to the shoulder 23a formed at the junction of the smaller andlarger bores of the body member H, but with a slight axial clearancewhen in its foremost position. This clearance constitutes a confinedpressure chamber 21. Opening into this clearance or pressure chamber isa pressure port leading from one of the fuel ducts. While such port maycommunicate either with the fuel supply duct or the pre-circulation duct(the pres sures in these ports being almost the same). in

the embodiment illustrated the pressure port 28 is shown leading to thelatter duct. The function of this port is to maintain in .the aforesaidI clearance or pressure chamber a pressure substantially equal to thatin the fuel system acting against the forward, annular face of theenlarged part 22 of the plunger, for opening the tip valve in a mannerto be described hereafter.

The enlarged part 22 of the plunger contains a coil compression spring29 urging the plunger forwardly and abutting plug 30 which is threadedlysecured within a well at the rear of the casing Hi, this well being aslightly enlarged continuation of the casing bore.- The enlarged part 22of the plunger and the spring 29, to-

gether with the pressure chamber 21 and pressure part 28 constitutepressure responsive means for moving the plunger forwardly in responseto a decrease in fuel pressure, and moving it rearwardly in response toan increase in said pressure. The well is closed by a threaded closureplug 3| provided with a sealing gasket 32 to render the casingoil-tight. The plug 30 also serves to retain the body member ll withinthe casing l0 and against the orifice plate H; for this purpose a spacerring 33, which may be of yieldable metal to effect a semi-seal, isinterposed between the rear end of the member ll and the plug. This ringhas a close fit with the bore of the casing, whereby both the casing andthe body member are sealed. The ring has an internal diameter smallenough to permit free rearward travel of the plunger 20.

The casing H has an annular groove 34 near cates with a spill returnline or spill outlet 35 provided with a throttle valve 39. Radial ports36 in the body member II are in constant communication with the groove34. Radial ports 31 in the enlarged part 22 of the plunger communicatewith an annular groove 38 formed on the outer wall of the part 22, andthe groove 38 is located for full registry with the ports 36 when theplunger is fully retracted, as shown in Fig. 8, and to be fully out ofregistry therewith when the plunger is in its foremost position, asshown in Fig. 1. The ports 36 and groove 38 constitute flow controlmeans for shutting off the spill return duct when the plunger isadvanced, while the valve 39 constitutes fiow control means forregulating the rate of flow through the spill return duct.

The fuel supply pipe 24, the pre-circulation pipe 25 and the spillreturn pipe are conveniently disposed at right angles to theburnercasing and all are grouped together at approximately the sameaxial position at the rear of the burner, as shown.

The burner operates as follows: Assuming the burner to be in theposition shown in Fig. 1, and the valve 26 open, fuel is supplied underpressure to the supply duct 24 and flows forwardly through duct I2 andinto the circumferential groove I4 in the inner body member II. Theswirl ports I5 being closed by the plunger 20, all of the fuel flowsback through the precirculation ducts I3 and 25 and valve 26. In thisphase of the operation the fuel circulates freely. It will be understoodthat heated fuel will be circulated when a cold burner, containingviscous fuel, is being prepared for operation, while cold or cool fuelis usually circulated when the burner is a nonoperating member of agroup of burners in the same furnace which it is desired to cool andprotect from damage by heat from the flame of other burners which are inoperation. In this condition of the burner the plunger 20 is urged bythe spring 29 into the foremost position in which the forward part 2027closes the swirl ports and the tip valve 2I closes the communicationbetween outlet orifice IB and the vortex chamber I6. The axial bores fluand 20a of the tip valve and plunger, respectively, are in communicationwith the outlet orifice, but are shut oil from the spill return duct 35because in this position of the plunger the groove 38 on the plunger isout of registry with the ports 36; hence, if there is any back pressurein the spill return duct 35 it will not cause dribbling of fuel throughthe forward end of the axial bores and through the orifice I8communicating therewith.

When it is desired to open up the burner the pre-circulation shut-offvalve 26 is closed. Pressure, transmitted through the port 28, nowbuilds up on the forward face of the enlarged part'22 of the plunger.This pressure causes the plunger to move rearwardly against the actionof the spring 29. In moving rearwardly it first opens the final outletorifice I8 for communication with vortex chamber I 6 and thereafteruncovers the swirl ports I5, thereby opening communication from thesupply duct I2 via the groove I 4 and the ports I5 to the swirl chamber.tip valve was previously opened free now of atomized fuel into thecombustion chamber outside of the orifice is permitted as soon as theports I5 are uncovered and a good spray is obtained from the start. Thefully open position Since the All of the slide valve in the spillpassage, (1. e., the

registry of the groove 38 with the ports) is attained at the completionof the rearward movement of the plunger, and partial communication isestablished even before the swirl ports I5 are uncovered, so that thereturn of fuel through the bores 2I a and 20a and the spill return duct35 can take place from the start. The amount of fuel discharged throughthe orifice I8 may be controlled by regulation of the throttle valve 39,either with or without a regulation of the fuel pressure in the supplyduct 24, as is well known in the art.

To shut down the burner and maintain precirculation the shut-off valve26 is opened. The pressure acting on the plunger is thereupon relievedvia the port 28 and duct 25 and the plunger is moved forwardly by thespring 29 to the position shown in Fig. 1, thereby first closing theswirl ports I5 to effect a sharp shut-off of the fuel flow, andpreventing dribbling of fuel, which would result if the tip valve 2|were first seated. The plunger will, of course, also move to theposition of Fig. 1 upon cessation of the supply of fuel through the duct24.

I claim as my invention: a

1. A burner for liquid fuel having a nozzle portion provided with anorifice means, said nozzle having a wall structure defining apre-orifice chamber; a fuel supply duct communicating with saidpre-orifice chamber for admitting fuel into said chamber; a fuelpre-circulation duct communicating with said fuel supply duct at a pointin close proximity to and externally of said chamber; flow control meansbetween said chamber and the juncture of said ducts for controlling theadmission of fuel from said supply duct into said chamber; meansresponsive to the pressure of fuel in one of said ducts for opening saidflow control means to admit fuel from said supply duct into said chamberin response to a rise in said pressure and for closing said flow controlmeans to prevent the admission of fuel into said chamber in response toa drop in said pressure; and means for varying the fuel pres sure insaid ducts.

2. A burner for liquid fuel comprising an elongated body having a nozzleportion at the forward end thereof provided with an orifice means. saidnozzle having a wall structure defining a pre-orifice chamber; a fuelsupply duct extending generally longitudinally with respect to said bodyto a point contiguous to said pre-orifice chamber; one or more fueladmission ports connecting the fuel supply duct with the pre-orificechamber; a fuel Dre-circulation duct extending longitudinally withrespect to said body to a point contiguous to said pro-orifice chamberand communicating with said fuel supply duct at said point externally ofsaid chamber; valve means for selectively opening or closing said fueladmission ports; a pressure responsive device connected to one of saidducts to receive pressure therefrom. having a movable element exposed tosaid pressure for movement in a first direction in response to anincrease in said pressure; resilient means urging said movable elementin a second direction opposed to said first direction; means connectingsaid movable element to said valve means for opening said fuel admissionports when said ele ment moves in said first direction to admit fuelfrom the fuel supply duct into said chamber and for closing said fueladmission ports when said element moves in said second direction to pre-I vent the admission of fuel into said chamber;

flow of fuel through said pre-circulation duct.

3. A burner for liquid fuel having a nozzle portion provided with anorifice means, said nozzle having a wall structure defining apre-orifice vortex chamber; one or more swirl ports in said wallstructure disposed substantially tangentially to the chamber foradmitting fuel into the chamber to form a vortex therein; a fuel supplyduct communicating with said vortex chamber through said swirl ports; aspill return duct communicating with said vortex chamber for the returntherefrom of fuel; a fuel pre-circulation duct communicating with saidfuel supply duct at a point in close proximity to and externally of saidchamber; flow control means for regulating the flow of fuel through saidswirl ports; means responsive to the pressure of fuel in one of saidducts for opening said flow control means to admit fuel from said supplyduct through said swirl ports into said chamber in response to a rise insaid pressure and for closing said flow control means to prevent theadmission of fuel into said chamber in response to a drop in saidpressure; and means for varying the fuel pressure in said ducts.

4. A burner for liquid fuel having a nozzle portion provided with anorifice means at the front end thereof, said nozzle having a wallstructure defining a pre-orifice vortex chamber; one or more swirl portsin said wall structure disposed substantially tangentially to thechamber for admitting fuel into the chamber to form a vortex therein; aslide valve mounted movably with respect to said wall structure forselectively covering or uncovering said swirl ports to control the flowof fuel therethrough; a tip valve within the vortex chamber adapted toseat against said orifice means to shut ofl communication from thevortex chamber to the orifice, said tip valve being connected to saidslide valve so that the tip valve is seated when the slide valve ismoved in a direction to cover said swirl ports, and viceversa; a bore insaid tip valve open at the front end thereof for the return of fuel fromthe vortex chamber when the tip valve is retracted from the orificemeans: a spill return duct connected to said borein the tip valve; afuel pro-circulation duct communicating with said fuel supply duct at apoint in close proximity to and externally of said chamber; and meansfor actuating said slide valve and tip valve.

5. In combination with the burner according to claim 4, fiow controlmeans for controlling the flow of fuel through said spill return ductconnected for operation with said slide valve so that the spill returnduct is closed when said slide valve is moved in a direction to coversaid swirl ports, and vice versa.

6. The burner according to claim 4 wherein the slide valve and tip valveare so connected that the tip valve is unseated before the swirl portsare uncovered when the valves are moved in a direction opposite to thesaid direction.

7. A burner according to claim 4 wherein the slide valve is axiallymovable with respect to the wall structure of the vortex chamber and isrigidly connected to said tip valve.

8. A burner for liquid fuel having a nozzle portion provided with anorifice means, said nozzle having a wall structure defining a preorificevortex chamber; one or more swirl ports in said wall structure disposedsubstantially tangentially to the chamber for admitting fuel into thechamber to form a vortex therein; a fuel supply duct communicating withsaid vortex chamber through said swirl ports; a swirl port valve forselectively opening or closing said swirl ports; a tip valve within thevortex chamber adapted to seat against said orifice means to shut offcommunication from the vortex chamber to the orifice; an axial bore insaid tip .valve aligned with said orifice for communication with saidorifice when the tip valve is seated and for the return of fuel from thevortex chamber when the tip valve is retracted from the orifice means; aspill return duct connected to said bore in thetip valve; a displaceablemember for opening both said swirl port valve and tip valve when thedisplaceable member is moved in one direction and closing both saidvalves when the displaceable member is moved in the opposite direction;a fuel pre-circulation duct communicating with saidfu'el supply duct ata pointin close proximity to and externally of said chamber; and meansfor shutting off the flow of fuel in said fuel pre-circulation duct.

9. In combination with the burner according to claim 8, throttling meansin said spill return duct for adjusting the flow of oil through saidduct, and a shut-ofi valve connected to said displaceable member so thatthe spill return duct is open when said displaceable member is moved inthe said direction to open the tip valve, and the spill return duct isclosed when the displaceable member is moved in said other direction.

10. In combination with the burner according to claim 8, meansresponsive to the pressure of fuel .in said fuel supply duct and fuelpre-circulation duct for moving said displaceable member in the saiddirection when the said pressure increases and to move said displaceablemember in the said other direction when the said pressure decreases.

11. A burner for liquid fuel having an elongated, tubular body having avortex chamber at its forward end and an end wall with an outletorifice; one or more swirl ports in the side wall of said vortex chamberdisposed substantially tangentially to the chamber for admitting fuelinto the chamber to form a vortex therein:

a fuel supply duct extending longitudinally with respect to said bodyand communicating at its forward end with said vortex chamber throughthe swirl ports; a fuel pre-circulation duct extending longitudinallywith respect to said body and communicating with said fuel supply ductat said forward end externally of said vortex chamber; a reciprocableplunger within said body having a part thereof within the vortex chamberin engagement with the side wall containing said swirl ports andterminating in advance of said swirl ports, so as to cover said swirlports when the plunger is in its forward position and to uncover saidswirl ports when the plunger is retracted; a tip valve at the forwardend of said plunger and within said vortex chamber aligned with saidorifice and adapted to seat against said end wall to shut offcommunication from the vortex chamber to the orifice when the plunger isin its forward position and establish said communication when theplunger is retracted; an axial bore extending through at least theforward part of said plunger and through said tip valve aligned withsaid orifice for communication with said orifice when the tip valve isseated and for the return of fuel from the vortex chamber when the tipvalve is retracted from the end wall; a spill return duct incommunication with said axial bore; valve means for said spill returnduct responsive to the position of said plunger for shutting off saidspill return duct when the plunger is in its forward position and foropening the spill return duct when the plunger is re-' and means forreciprocating said pressure; and a valve in the pre-circulation duct forshutting off the flow of fuel therethrough.

13. A burner for liquid fuel having an elongated tubular body having aconfined vortex chamber at its forward end and an end wall with anoutlet orifice; an annular groove in said body surrounding said swirlchamber and separated by an annular wall from said swirl chamber; one ormore swirl ports in said annular wall communicating at their outer endswith said groove and having their inner ends disposed substantiallytangentially to the chamber for admitting fuel into the chamber to forma vortex therein; a fuel supply duct communicating with said annulargroove; a fuel pre-circulation duct communicating with said groove at apointspaced from said fuel supply duct, whereby fuel supplied throughthe fuel supply duct must flow through said annular groove beforeentering said precirculation duct; and valve means within the vortexchamber for covering and uncovering said swirl ports.

14. In combination with the burner according to claim 13, a spill returnduct within said body communicating with the rear of said vortexchamber. 7

15. In combination with the burner according to claim 13, a tip valvewithin the vortex chamber adapted to close the outlet orifice having acontrol plunger extending rearwardly from the vortex chamber, and borewith said plunger forming a spill return duct communicating with saidvortex chamber.

16. A burner for liquid fuel having an elonnear the forward end thereofand communicating with said fuel supply duct; one or more swirl portsbetween said groove'and the swirl chamber disposed substantiallytangentially thereto for admitting fuel into the chamber to form avortex therein; a longitudinal fuel pre-circulation duct within saidcasing communicating at its forward end with said groove; a pressureport connecting one of said ducts to the enlarged rear part of the boreof the body member; a reciprocable plunger within the bore of said bodymember having a hollow enlarged rear part within said enlarged rearpartof the bore of the body member and extending forwardly into the vortexchamber, said enlarged rear part of the plunger presenting a forwardlydirected face exposed to fuel pressure transmitted through said pressureport, at least the part of the plunger within the vortex chamber havinga close fit with the chamber wall, said part of the plunger terminatingin advance of said swirl ports, so as to cover said swirl ports when theplunger is in its forward position and to uncover said swirl ports whenthe plunger is retracted; a tip valve at the forward end of said plungerand within said vortex chamber aligned with said oriflea and adapted toseat against said end wall to shut off communication from the vortexchamber to the orifice when the plunger is in its forward position andestablish said communication when the plunger is retracted; an axialbore extending through the plunger from said hollow enlarged rear partthrough said tip valve aligned with said orifice for communication withsaid orifice when the tip valve is seated and for the return of fuelfrom the vortex chamber when the tip valve is retracted from the endwall; resilient means urging said plunger forwardly in opposition to thefull pressure acting on said forwardly directed wall of the plunger; aspill return port through the body member at said enlarged rear partthereof; a port in said hollow enlarged rear part of the plungerpositioned for registry with said spill return port when the plunger isretracted and for displacement out of registry therevith when theplunger is in its forward position; ,nd means for shutting off the fuelpre-circulation duct at a point beyond said pressure port.

JOHN RUSKIN JOYCE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Num er Name Date 1,252,254 Fisher Jan. 1, 19182,015,611 Wettstein Sept. 24, 1935 2,079,430 Bargeboer May 4, 19372,345,402 Lubbock et a1 Mar. 28, 1944

